Way to exit grim vessel (3)
I believe the answer is:
ark
'vessel' is the definition.
(ark is a kind of vessel)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for ark that I've seen before include "Rescue ship" , "Noah's boat" , "-- of the Covenant" , "See 18 Down" , "Boat built to withstand great flood" .)